The present invention relates to a file system which is excellent in providing redundancy and exhibits an excellent read performance.
For access to a disk drive mounted under an operating system (OS), a file system allows a data file to be divided to several blocks, written into a single volume, and read from the single volume on a block basis.
As a known technique for a file system ensuring redundancy of a data file, U.S. Pat. No. 5,724,500 discloses a method in which backup regions of volumes are each divided to a number corresponding to a given number of cylinders provided in each multiwritten volume, pieces of data from the backup regions each divided to the given number are inputted concurrently and parallelly, and the inputted pieces of data are outputted to a backup destination in the order of the cylinders through a buffer within a CPU, thereby reducing backup time for the multiwritten volumes remarkably.
Furthermore, there is known a technique in which, when a disk controller in a storage system receives a write request from a host computer, the disk controller issues the same write request to a mirror disk drive in the same pair (refer to JP 2003-157151 A).